Such a method is described in U.S. Pat. specification No. 5,699,955 according to which two Ti-pipes are firmly joined by solid diffusion bonding. The pipes are butted and heated under pressure in a non-oxidizing atmosphere, while a Ti-layer is disposed at the interface of butting by either (1) inserting a sheet for bonding made of Ti having a thickness of 500 μm or less between the butted faces, or (2) previously forming a Ti-layer for bonding having a thickness of 1 μm or more on at least one of the butted faces by any method such as vapour deposition.
A drawback of this method is that the butted ends must be very carefully prepared and aligned at high accuracy before being pressed together to being bonded.
Current premium pipe joining technology uses a metal-to-metal contact area or a rubber or Teflon seal ring to effect a seal in a threaded connection. Even with such a seal, leaks are often experienced in the connection. This is undesirable in most applications. Leaks become even more common and troublesome when a threaded connection is radially expanded.
To overcome the above drawbacks the present inventors propose the following method.